Design and tests of a hybrid servo drive system for a 1000 T mechanical press

Large mechanical presses are used in the automotive industry to produce parts out of sheet metal. Servo presses can improve productivity by opening and closing presses faster, while at the same time improving quality by pressing slower. However, such servo presses require very high electrical peak power, resulting in high investment cost for both presses and the electrical installation of press shops. This paper presents an alternative, hybrid servo-press design. Here, the classical flywheel of the mechanical press is maintained to give peak power during pressing, while a relatively small servo drive gives the press its high performance. First measurements on a 1000 T press demonstrate the feasibility of the concept and confirm the simulations. The proposed hybrid servo press design has a peak power of only little more than an equivalent mechanical press, and typically improves press-line performance by 10-30%.